Television



H. P. DONLE Nov. 6, 1934.

TELEVISION Filed Nov. 28 1928 2 Sheets5heet l M aucsmzm a U H aum Hafold PDwzZc.

mwhbinzmmp. 29E 51521 M INVENTOR Y E- N H. P. DONLE Nov. 6, 1934.

TELEVIS ION Filed Nov. 28, 1928 2 Sheets-Sheet 2 EEdz lll| EE1E2 HamZd PfionZ e UUKDOW U61:-

INVENTOR WW Patented Nov. 6, 1934 A i UNITED STATES PATENT OFFlCE- TELEVISION Harold P. Donle, Meriden, onn., assignor to gadlio Inventions, Inc., a corporation of New Application November 28, 1928, Serial No. 322,360

'2 Claims. (01. 178-695) In the present state of the art, television or system embodying my invention and utilizing image transmission either by wire or by radio radio frequency transmission. requires some method of synchronizing a cer- Fig. 2 is a detail view of the transmitting tain device at the receiving station usually scanning disc. termed the scanning disc with a somewhat Fig. 3 is a detail view of the receiving scan- 6 similar device at the transmitting station. It ning disc and the synchronizer. is absolutely essential that these scanning de- Fig. 4 is a diagrammatic view of a modification vices run in perfect synchronism. Several methof the transmitter. ads have been proposed to maintain this syn- Fig. 5 is a detail view of a modified form i0 chronism. of the transmitting scanning disc.

One method which has been employed is to Fig. 6 is a diagrammatic view of'a system emcontrol or adjust the speed of the motor drivploying a wire line or channel for the circuit of ing the receiving scanning disc by hand and so transmission. endeavor to keep it in step with the transmit- The picture or image to be transmitted is ter. This method has been found generally undiagrammatically indicated at 10 and may of 70 satisfactory and extremely critical of control. course represent an actual object or a moving Another method heretofore employed consists film. The transmitting scanner 11 is driven by in sending from the transmitter to the receiver a suitable motor 12 and provided with one or synchronizing impulses at a difierent carrier more series of apertures 13 arranged spirally frequency from that of the image impulses. and through which the light from the image 75 This method is particularly objectionable in passes to a light sensitive cell 14. The output radio transmission as it necessitates the employof this cell preferably passes through an amment of two channels or wave lengths. plifier 15 and a radio frequency transmitting de- It is of course possible'to drive the transmitter vice 16 provided with a suitable output antenna and receiver from the same A. 0. power line 17 and so forth. 80 but this is not of general utility, because the re- At the receiving end is located a suitable pickceivers can seldom use the same line and in fact up antenna 18, and radio receiving and ampliwould usually have to rely upon an independent fying means 19. The output of this receiver source of power. is connected to a suitable light source 20 such One method of synchronizing, described in my as a so-called neon lamp. co-pending application, Ser. No. 306,390, filed The scanning disc 21 of the receiving end is Sept. 17, 1928, now Patent No. 1,903,986, utilizes, provided with a series of apertures 22 correfor synchronizing purposes, the .line frequency sponding with the apertures 13 in the transmitof the television image. ter disc and is driven by a motor 23 of any I have discovered, however, that it is possible suitable type at approximately the speed of the 9 to transmit, independently, a television signal motor 12 so that the image will be visible at and a synchronizing signal over one circuit or 24 either on a screen or through a lens or in a at one carrier frequency by taking advantage of frame as usual in systems of this character. visual persistence. For example, by transmit- The synchronizing of the'disc 21 with the disc 46 ting television impulses for a given period of 11 is accomplished through an electro-magnetic 95 time and then discontinuing this transmission system utilizing light actuating impulses derived to transmit a synchronizing impulse over the from the transmitting station. Attached to or same circuit. During the transmission of the rotatable with the receiving disc 21 is an armasynchronizing impulse the light source at the ture 25 having one or more bars 26. A number receiver is interrupted but due to the comparaof electromagnets 27 are arranged to correspond 100 tively sluggish action of the retina no visual with the number of armature bars 26. The sensation is caused by this interruption. coils of these magnets are connected to the The main object of my invention therefore is amplifier 28 which in turn is arranged in shunt to; produce a simple inexpensive and reliable with a resistance 29 in the receiving circuit. 0 synchronizing system requiring but one channel The transmitting disc 11 is provided with a 9 for both image a Synchronizing pulses. number of openings 30 corresponding with the Another object is to provide a system in which number of magnet coils and armature bars. the energy of the syn h on ing impulses is in- It will be noted that there are no apertures dependent of the intensity of the light impulses. in the receiving disc 21 in alignment with the Fig. 1 is a diagrammatic view of a television armature bars 28. no

As the transmitting disc rotates, the picture apertures 13 are successively passed between the picture or source of light and the energizing cell 14. This causes the rapid succession of picture impulses which are amplified and transmitted and received in the usual manner. When one of the openings 30, which may be termed a synchronizing opening passes in front of the light source, the cell 14 will receive a very' powerful light impulse which is transmitted in the usual manner and over the same channel as the picture impulse. This synchronizing impulse is amplified and energizes the magnets 2'7 so as to either retard or speed up the receiving disc 21 depending upon the position of the armature bars relative to the poles of the magnets. These synchronizing impulses also tend to light the lamp 20 but as there is no picture aperture in the disc 21 corresponding in angular relation to the position of the magnets 2'7, there will be no visual indication of the arrival of the synchronizing impulses.

In Fig. 4 I have shown a modified arrangement in which there are two separate cells 14 and 14' respectively, for the picture impulses and the synchronizing impulses. In such an arrangement it is possible to design the cells and sources of light 10, 10', so as to adapt them to their respective functions, namely, picture control and synchronization.

In 'the form shown in Fig. 5, it will be seen that the disc 35 has the synchronizing openings 36 entirely inside of the group of picture apertures. 37. This makes it possible to arrange the picture light source 10 separate from the synchronizing light source 10.

It will be understood that a receiving disc and synchronizer similar to. the one shown in Fig. 3 may be used with a system employing a'scanning disc of the type shown in Fig. 5. Light from the receiver light source will of course be cut off by an unperforated portion of the receiving scanner at the instant when the synchronizing impulse is being received.

The arrangement shown in Fig. 6 is intended to typify a wire line of communication in which the conductors 40 constitute the communicating channel connecting the transmitting amplifier 41 with the receiving amplifier 42. Otherwise this system is similar to the foregoing except that of course the constants of the circuits are suitable for wire line transmission rather than for radio frequency transmission.

It will be apparent from the foregoing that the picture impulses of the synchronizing impulses are transmitted over the same channel or circuit and that the synchronizing impulses may be wholly independent of the light intensity of the picture source.

It should be understood that the picture apertures in the transmitting and receiving scanners may be of any suitable size, number and arrangement although preferably in what is comter having a scanner, a receiver having a scanner, with a channel of communication between them, independent means for rotating said scanners and means utilizing the same channel of communication for automatically synchronizing the receiving scanner independently of .the light value of the transmitted image, said transmitting scanner having a train of apertures adapted to scan the complete picture area and also having a larger aperture, said receiving scanner having a train of image apertures similar to the apertures in the transmitting scanner and a non-perforated portion corresponding to said larger aperture, said larger aperture and said non-perforated portion being similarly located with respect to the trains of picture apertures in the respective scanners.

2. In a television receiver a light source, a scanning member having a train of picture apertures and a non-perforated portion for screening said light sourceafter the completion of a train of picture impulses less than the total number of impulsesv required for reproducing a complete image and greater than the number required for producing a single line thereof, a.

motor for driving said scanning member and a synchronizer for said scanning member including an electro-magnetic system having one member moving at a speed always proportional to the speed of the scanning member.

3. The method of synchronizing television systems which includes alternately scanning a series of discrete paths, said series of paths being scanned successively and each path of said series being scanned without interruption thereof,'the total length of said series being greater than any linear dimension of the image to be transmitted, interrupting the scam ing and transmitting a synchronizing signal over the same channel of communication, said series of discrete paths being in sum less than the totality of paths necessary for a complete scanning of the image to be transmitted.

4. Television apparatus comprising a transmitter having a scanner with a plurality of apertures, a receiver having a scanner with a plurality of apertures corresponding to the transmitter apertures, most of which are for, scanning the subject and at least one of which is not for scanning but cooperates with a synchronizing light source, a channel of communication between the transmitter and the receiver, said receiving scanner having an opaque spot corresponding with each aperture cooperating with the synchronizing light source and having electro-magnetic means receiving its energizing impulses over the same channel communication for synchronizing the receiving scanner at intervals between received groups of image signals, the totality of each group of signals being less than a complete image scanning but an integral fraction thereof and, being an integral multiple of the signals required for scanning a single line thereof.

5. A television system including means for transmitting repeated groups of picture signals, each group representing an integral fractional part of the entire picture, said part being formed of a series of immediately adjacent continuously scanned lines of said picture, said series constituting less than a complete picture scanning and means for transmitting synchronizing signals independently of and solely between said groups of picture signals.

6. In a synchronized television system, means for transmitting and receiving a complete image characterized by the division of said image into a plurality of strips, each such strip comprising a plurality of immediately adjacent continuously scanned lines, means for transmitting a synchronizing signal during a finite interval of time only at the completion of transmission of signals corresponding to each of said strips, and

bands being displaced in time by the interval required for the transmission of a synchronizing signal at the end of each band, and means at the receiver for compensating for the time-displacement of said bands whereby a correctly reconstructed image is produced.

HAROLD P. DONLE. 

